1. Technical Field
The present invention relates generally to a patch antenna for a shark fin antenna for a vehicle and, more particularly, to a multilayer-type patch antenna which is built in a shark fin antenna for a vehicle and receives signals within GPS, GLONASS, and SDARS frequency bands.
2. Description of the Related Art
As well known to those skilled in the art, a shark fin antenna for a vehicle is used to improve signal reception rates of electronic devices installed within a vehicle. A shark fin antenna is usually installed outside a vehicle. For example, Korean Patent Application Publication No. 10-2011-0066639 (titled “Antenna Device for Vehicle”) and Korean Patent Application Publication No. 10-2010-0110052 (titled “Antenna Device for Vehicle”) disclose various types of shark fin antennas for a vehicle.
As recent vehicles are equipped with electronic devices such as a navigation system, a DMB system, and an audio component, a plurality of antennas are built in a shark fin antenna to receive signals within multiple frequency bands, including frequency bands for GPS (U.S.A), GLONASS (Russia), SDARS (operated by Sirius XM), Telematics, FM, and T-DMB.
However, there is a problem that it is difficult to mount all the necessary antennas, for example, antennas for GPS, GLONASS, SDARS, Telematics, FM, and T-DMB within a limited area of a shark fin antenna.
There is another problem that since GPS and GLONASS are selectively used depending on country, a shark fin antenna for vehicle needs to be selectively equipped with either an antenna for GPS or an antenna for GLONASS
When each shark fin antenna is not equipped with both GPS and GLONASS antennas but equipped with only a GPS or a GLONASS antenna, shark fin antennas have to be produced on different production lines. This leads to an increase in the production cost of such shark fin antennas. For this reason, many manufacturers are trying to develop shark fin antennas equipped with antennas for both GPS and GLONASS signals.
Conventional patch antennas for GPS are designed to receive signals within a frequency band of about 1576 MHz so that these patch antennas cannot receive a GLONASS signal which has a frequency of about 1602 MHz.
Accordingly, in order for shark fin antennas to pick up both of the GPS and GLONASS signals, each shark fin antenna has to be equipped with antennas for both GPS and GLONASS signals.
However, since recent shark fin antennas are necessarily equipped with antennas for SDARS, Telematics, FM, T-DMB, etc., there is difficulty in designing a shark fin antenna that can accommodate both GPS and GLONASS antennas because of its limited area. Furthermore, the structure of conventional shark fin antennas that has both GPS and GLONASS antennas has the disadvantage of increasing the production cost of shark fin antennas.